1. Technical Field
The present invention relates to a redundant I/O module comprised of a control I/O module that communicates with a controller and that has an IOM setting information holding section that stores IOM setting information downloaded from a high-level apparatus and a standby I/O module that has the IOM setting information holding section.
2. Related Art
The present invention provides a function of automatically loading IOM setting information for a replaced I/O module at the time of replacement of a redundant I/O module for interfacing between a controller of a distributed control system and plant equipment to be controlled. An IOM automatic loading function is a function of automatically loading IOM setting information required for operation of an I/O module into an I/O module by means of a controller.
FIG. 2 is a functional block diagram for describing a related-art IOM setting information downloading technique in a distributed control system. A control bus 10 is connected to a controller 20 and controls plant equipment 50 by way of a redundant control I/O module 30 or a redundant standby I/O module 40.
The control bus 10 is connected to an operation monitoring device 60 and communicates with the controller 20. An operator 70 monitors and operates the operation monitoring device 60. Further, the control bus 10 is connected to an engineering PC and communicates with the operation monitoring device 60.
The controller 20 has the IOM status generation section 21 and the IOM downloading section 22. The standby I/O module 40 has the IOM setting information holding section 41, the IOM status information holding section 42, and the IOM setting information receiving section 43. Although unillustrated, the control I/O module 30 is also configurationally identical with the standby I/O module 40 and has the IOM setting information holding section 31, the IOM status information holding section 32, and the IOM setting information receiving section 33.
The operation monitoring device 60 is equipped with a message window 61 and an IOM download window 62. An engineering PC 80 is equipped with an IOM setting information database 81 that generates, by means of engineering, IOM setting information to be downloaded and holding the thus-generated information.
In consideration of a power failure, or the like, the IOM setting information holding sections 31 and 41 of the I/O modules 30 and 40 are stored in nonvolatile memory. Therefore, when the I/O modules are replaced, the IOM setting information must be downloaded again.
FIG. 2 shows a status achieved immediately after the standby I/O module 40 has been replaced for reasons of a failure through maintenance operation. Operation performed when IOM setting information is downloaded from the engineering PC 80 into the IOM setting information holding section 41 of the standby I/O module 40 is hereinbelow described.
The IOM status generation section 21 of the controller 20 detects replacement of the standby I/O module 40 by making a reference to the IOM status holding section 42 of the standby I/O module 40 and transmits a message to the message window 61 of the operation monitoring device 60.
Glancing at a message showing replacement of the standby I/O module 40 by reference to the message window 61, the operator 70 makes a reference to IOM setting information to be downloaded from the IOM setting information database 81 of the engineering PC 80 by means of operating the IOM download window 62, and transmits the acquired IOM setting information to the IOM download section 22 of the controller 20.
The IOM download section 22 of the controller 20 transmits the received IOM setting information to the IOM setting information receiving section 43 of the standby I/O module 40. The IOM setting information receiving section 43 stores the received IOM setting information into the IOM setting information holding section 41. As a result of storage of the IOM setting information, the standby I/O module 40 starts I/O operation in accordance with new IOM setting information.    [Patent Document 1] JP-A-2001-109704
When new IOM setting information is downloaded at a plant after replacement of a broken-down I/O module, a related-art downloading technique encounters the following problems.
(1) Message check to be performed by the operator 70 and IOM loading operation are required, and replacement maintenance procedures are complicate. Further, IOM loading operation cannot be carried out without the operator.
(2) In order to acquire new IOM setting information, the engineering PC 80 must be connected to the control bus 10. An operation monitoring device and a controller which are to be operated by an operator are occasionally provided at a remote place, and many plants are not permanently equipped with an engineering PC. For this reason, an engineering PC must be carried to the remote location at the time of IOM loading operation, which poses heavy burdens on workers.